The rotary embossing of continuous strip material has usually been carried on in the past by passing the strip material through a pair of embossing rollers. The embossing rollers were usually manufactured of steel or the like and had complementary mating male and female formations for making indentations in the strip material.
This type of procedure worked relatively satisfactorily for soft material such as paper etc., however, it was not entirely satisfactory for the embossing of continuous strip sheet metal. Accordingly, it has been proposed to emboss continuous strip sheet metal such as thin steel strip by subjecting the steel strip to the action of complementary male and female embossing rolls, while maintaining the strip under tension between sets of tensioning rolls located up stream and down stream of the embossing rolls. One such system is disclosed in Canadian Pat. No. 820,611 dated Aug. 19, 1969 inventor Ernest R. Bodnar.
In such a system however it was necessary to manufacture the down stream set of tension rolls as that they fitted into the indentations already embossed by the embossing rolls. In addition it was necessary that the down stream set of tension rolls should be precisely synchronized with the embossing rolls so that the die formations of the tensioning rolls fitted within the indentations already formed in the steel strip by the embossing rolls. Consequently, it was a relatively expensive structure, and one which required to be carefully set up and adjusted to run satisfactorily.
It has also been proposed to form such transverse indentations without subjecting the steel to tension, see for example U.S. Pat. No. 3,137,922, Schumacher. This process however was not satisfactory since the steel strip tended to be distorted by the embossing action of the embossing rolls.
The end product of such a system namely embossed strip sheet metal is possessed of many desirable qualities. For example, it is inherently more rigid than flat sheet material. In addition, it may be provided with an attractive surface patterning, and it may be desirable for a variety of other reasons.